Senior Cats Fed Only Wet Food May Be Eating Less Than They Need
Published
Based on a peer-reviewed in-home feeding study of 134 cats aged seven and older, published in Animals (2026), cross-checked against the full text on PubMed Central and against AAHA/AAFP feline life stage guidelines.
A study that tracked 134 cats aged seven and up through automated feeders found that on an all-wet diet the cats ate roughly half the calories they ate on an all-dry diet, and on average less than a standard daily energy estimate suggests. A mixed wet-and-dry diet came closest to that estimate.
A cat that grazes, not one that dines
A new feeding study followed 134 cats aged seven and older in their own homes, using automated feeders that weighed every bite. The researchers wanted to know how much an aging cat actually eats over a full day when food is always available, and whether that changes depending on whether the bowl holds dry kibble, wet food, or both. Many owners assume a softer, wetter diet is the kinder choice for an older cat. The results give them a reason to check.
The study was published in the journal Animals in late 2025, although the feeding itself took place in UK homes in late 2019. It was run by researchers at Waltham Petcare Science Institute and Royal Canin, both part of Mars Petcare. Cats in two age brackets, seven to eleven and twelve and up, each spent time on three feeding regimens in a rotating order: an all-dry diet, an all-wet diet, and a mix of both. Every cat served as its own comparison across all three. Smart feeding stations recorded the exact time and weight of every visit to the bowl.
Anyone who has watched an older cat closely will recognize the first finding. These cats were not eating two square meals. They ate in short, frequent visits throughout the day, averaging six meals on the dry diet and closer to seven on the wet and mixed diets, clustered heavily around dawn and dusk. Most feeding happened between about 6:30 in the morning and 6:30 in the evening, with a clear lull overnight and another through the middle of the day. Cat behavior research has shown this pattern before. Confirming it in 134 ordinary house cats, in their actual homes rather than a research colony, is a different kind of evidence than a small lab study can offer.
The calorie figures stood out more. On the all-dry regimen, cats ate an average of 262.6 kcal across 24 hours. On the mixed wet-and-dry regimen, that fell to 222.6 kcal. On the all-wet regimen it dropped to 138.1 kcal, roughly half of what the same cats ate on dry food alone. The wet-food figure was significantly lower than both of the others.
For comparison, the researchers used a standard formula that estimates a cat's daily energy needs from body weight. A four-kilogram cat with moderate activity is estimated to need around 208 kcal a day. The cats on the all-wet diet, averaging 138 kcal, fell well under that mark, while the cats on dry food went well over it. The mixed group landed closest. The benchmark is rough, though. The study did not record the cats' weights, so their real needs are unknown, and the authors point out that indoor cats like these are probably less active than the formula assumes.
Why the gap exists, and why it is not really about brand
A cat's stomach is small, and wet food takes up a lot more of it per calorie. The authors suggest stomach fill may have limited how much the cats could eat on the all-wet diet. Average meal sizes fit that explanation: cats ate about 11 grams of dry food per meal for roughly 41 to 43 kcal, against 21 to 24 grams of wet food per meal for only about 19 to 22 kcal. The cats did not eat less often on wet food. If anything, they ate slightly more often. The extra visits were nowhere near enough to make up for the smaller meals.
That comes from the food format itself and says nothing about any particular bag or can. The three test diets happened to be Royal Canin's own senior lines, which raises a funding question taken up further down. But a given weight of wet food carries far fewer calories than the same weight of dry food, whatever the brand, because wet food is mostly water and dry food is not.
The study also measured a real advantage of wet food. Cats on the all-wet diet drank the least water from a bowl, yet their total water intake, counting the moisture already in the food, was more than double that of cats on dry food alone: 179.3 grams a day against 65.9 grams. The authors explain that cats inherited a weak thirst drive from a wild ancestor that got most of its water from prey. That leaves cats prone to lower urinary tract disease, a risk that appears to rise with age, and wetter diets have been shown to dilute urine and lower the risk of one common type of bladder stone. So there is no case here for giving up wet food, only for keeping an eye on how much of it gets eaten.
What this does and does not prove
A few caveats matter before anyone changes how they feed an older cat based on this study alone. The main analysis used only the last two days on each diet. Adding the four settling-in days before them, six days in all, gave nearly the same numbers. And because no weights were recorded, there is no direct evidence that any cat lost weight or muscle. What the data show is that calorie intake on an all-wet diet fell short of a standard estimate, and the authors consider a shortfall over a few days unlikely to matter on its own. The researchers also note that cats can take weeks or months to adjust their intake upward on a lower-calorie-density diet, which a study this short was not designed to catch. A cat that free-feeds on wet food for years, rather than six days, may settle into a different equilibrium than this snapshot suggests.
Age made no measurable difference. Cats seven to eleven and cats twelve and older ate about the same number of meals and the same calories. The AAHA and AAFP feline life stage guidelines call cats seniors from just over ten years, but the authors chose twelve as their cut-off, citing general agreement that cats enter the senior stage from around that age. The study was also limited to healthy cats: cats with diagnosed conditions, dental problems or special diets were excluded, so it says nothing about the frail or ill older cats that most worry owners.
If your older cat eats only wet food
If an older cat already eats a mixed diet and keeps a good body condition, nothing here calls for a change. This study matters most for owners who moved an aging cat to an all-wet diet, often believing it gentler or more natural, and have not checked since whether the cat's weight, muscle, and energy have held up. A cat can graze contentedly at a full bowl of wet food all day and still run a calorie deficit. It has no obvious way of showing that, short of slowly losing condition over months.
There is no need to panic or switch overnight. Check instead. Feel along the spine and hips for thinning muscle, look at the waistline from above, and if you have any doubt, ask for a body condition score at the next vet visit rather than judging by how eagerly the cat eats. If a cat is losing condition, talk to the vet before changing its food. The study's authors favor a mix of wet and dry for older cats, but they did not test what that does to body weight over months, and a cat with a health condition may need a different plan.